Clutch comprising a spring device and method for operating the same

ABSTRACT

The invention relates to a clutch, particularly a multi-disk clutch, of an, in particular, manual transmission for, in particular, vehicles having a spring force of a spring device, said spring force influencing the adjusting force, which is produced in a power source and which serves to actuate the clutch. This clutch should be able to operated while maintaining predetermined closing and/opening times that are as precise as possible. In addition, the closing and/or opening times should be independent of possible changes in properties of the spring device. To this end, a clutch of the aforementioned type is characterized in that the spring device ( 3 ) and/or at least one of its thrust bearings is provided with a sensor ( 4 ), which detects solid body changes and which serves to determine the spring force exerted by the spring device ( 3 ), and a device for transmitting the determined measured values for controlling and/or regulating the adjusting power source.

This invention relates to a clutch according the preamble of Patentclaim 1 and a method for operating such a clutch.

Operation of a generic clutch is influenced by the properties of thespring mechanism, among other things. The spring force produced by thespring mechanism can vary due to the manufacturing or can be varied as afunction of operating time.

A power-shift transmission such as an infinitely variable, automaticpower-shift transmission for vehicles having a generic clutch is knownfrom German Patent DE 198 22 193 A1, which is a hydrodynamicallyoperated multi-disk clutch. The closing force of this clutch isgenerated by a hydraulic cylinder which actuates a piston acting on theclutch disks against the force of a plate spring. The opening force isapplied by the plate spring as a spring device of this clutch. Theopening of the clutch, which is produced by the plate spring, must occurduring an accurately predetermined period of time, i.e., within acertain time window, for optimum functioning of the shift transmission.To this end, the hydraulic pressure within the hydraulic cylinder, whichis responsible for the closing of the clutch, is monitored by pressuresensors and used as control and/or regulating variables for theoperation of the clutch. The measured values obtained by the pressuresensors depend on the temperature, among other things, due to the changein viscosity of the hydraulic fluid.

This invention relates to the problem of permitting opening and/orclosing of the clutch with the greatest possible time precision in ageneric clutch. Changes that may result from a change in the propertiesof the spring mechanism should also be reliably avoided.

This problem is solved with a generic disk clutch by a design accordingto the characterizing features of Patent claim 1.

Advantageous and expedient embodiments of this device are the object ofthe dependent claims 2 through 4.

An advantageous method of operating an inventive clutch is the object ofclaim 5.

In a spring device consisting of at least one plate spring or togetherwith a shaft spring, also known as an ondular washer, the sensor isadvantageously mounted directly on the at least one plate spring and/orshaft spring in an area not adjacent to a thrust bearing. It is ofcourse also possible to provide the sensor on a particular thrustbearing of the spring mechanism.

When using plate springs and/or shaft springs, it is especiallyadvantageous to provide as the sensor a piezoresistive amorphous carbonlayer (e.g., DLC (diamond-like carbon) layer) applied permanently to asurface area not in direct contact with a thrust bearing. The carbonlayer must have a thickness of only 10 nm to 500 μm, preferably 10 nm to20 μm. Such layers, which may be applied by a PVD (physical vapordeposition) method or a CVD (chemical vapor deposition) method and areused to produce sensors for determining the state of characteristics ofmechanical components, are described in German Patent DE 199 54 164 A1.Washers provided with measurement layers are known from German Patent DE198 31 372 A1 for monitoring non-positive connections.

An inventive method for operating a generic shift transmission consistsof controlling and/or regulating an adjusting force acting on the clutchby means of characteristic values of the spring mechanism determined ascurrent values by the sensor and/or its at least one thrust bearing.

The transfer of the measured values detected by the sensor may betransmitted in an especially advantageous manner via a telemetric signalpickup. The high measurement sensitivity of the inventive sensors isespecially suitable for a telemetric signal analysis. With respect tothe principle of telemetric signal analyzing methods applicable here,reference is made in the state of the art to German Patent DE 40 34 019C1, European Patent 0 533 709 B1 and German Patent DE 37 14 195 A1, forexample.

An advantageous exemplary embodiment to be explained in greater detailbelow is depicted in the drawing.

In this drawing, the only figure shows:

FIG. 1 a half section through a schematic diagram of a multi-disk clutchof a manual transmission according to German Patent DE 198 22 193 A1.

A first body 1 and a second body 2, each rotatably mounted, areinterconnectable in a non-positive manner by means of intermeshingdisks.

A pressure valve 5 is mounted on the second body 2 in a rotationallyfixed but axially displaceable manner. With this pressure valve 5, thedisks of the two bodies 1, 2 can be pressed together in a non-positivemanner for engaging the clutch.

To disengage the clutch, a plate spring serves as the spring mechanism 3by means of which the pressure valve 5 is shifted to achieve an openedstate of the clutch. A hydraulic pressure (not depicted in the drawing)acts on the pressure valve 5 to engage the clutch, namely acting againstthe force of the plate spring 3. The pressure valve 5 determines theduration of the opening of the clutch under the force of the platespring 3.

The plate spring 3 is provided with a DLC layer as the sensor 4. Themeasured values obtained by the sensor 4, similar to the current springforce of the plate spring 3, are preferably sent telemetrically to anelectronic analyzer unit, from which the measured values can be utilizedto control and/or regulate the adjusting force acting on the clutch. Thedeceleration force of the hydraulic pressure applied to the pressurevalve 5 counteracting the opening of the clutch should be part of theaforementioned actuating force and/or adjusting force acting on theclutch in the sense of the description of the present invention.

In the electronic analyzer unit, the actual measured values measured bythe sensor 4 can be modified to take into account the properties of thephysical state influencing these measured values in or on the springmechanism.

1-5. (canceled)
 6. A disk clutch, with which a first body (1) and asecond body (2) in which a pressure valve (5) to which a hydraulicpressure is applied is mounted in a rotationally fixed but axiallydisplaceable manner, can be connected to one another in a non-positivemanner via intermeshing disks that can be acted upon by the force of apressure valve (5), of a manual transmission for motor vehicles inparticular, with a spring force of a spring mechanism which influencesthe adjusting force produced by a power source for operation of theclutch, wherein the spring mechanism (3) and/or at least one of itsthrust bearings is/are provided with a sensor (4) which detectssolid-state changes for determining the spring force emanating from thespring mechanism (3) and a device for transmitting the measured valuesthus determined for regulating the adjusting power source, whereby adeceleration force of the hydraulic pressure applied to the pressurevalve (5) counteracting the spring mechanism in the opening of theclutch is part of the adjusting force or thrust force acting on theclutch.
 7. The clutch according to claim 6, wherein the spring mechanism(3) consists of at least one plate spring or a combination of a platespring with an ondular washer.
 8. The clutch according to claim 6,wherein the sensor (4) is designed as a piezoresistive, amorphous carbonlayer applied permanently to a surface area of the spring mechanism (3)or a thrust bearing thereof.
 9. The clutch according to claim 6, whereinthe sensor (4) is provided with means for a telemetric signal pickup.10. A method for operating a clutch according to claim 6, wherein theadjusting force acting on the clutch is controlled and/or regulated as afunction of characteristic values of the spring mechanism (3) currentlydetermined by the sensor (4) and/or its at least one thrust bearing.